I also like to mix up the treats so the dogs never know what to expect. All they know is that I'm the giver of yummy treats, and I will pay them for working for me!
Real Meat

For liver, it helps to bake it in the oven so it's a little drier and less messier to handle.

Freshpet Vital
Freshpet Vital is sold at pet stores like Petco, and is made of healthful yet delicious ingredients. The treats come in small bite-size pellets so they're very easy to use for training. You can cut the pellets into halves to get even more mileage. Dogs love this stuff!
Here's more info: http://freshpet.com/products/vitalcompletemealsdog/
Available at Petco, Petsmart and most major pet stores.
Natural Balance Dog Food Rolls

http://www.naturalbalanceinc.com/dogformulas/DFRolls.html
Available at Feed Trough (Waialua), Crazy Canine (Aiea), Petco and most major pet stores.
Yummy Chummies

Yummy Chummies are available at Costco and come in a bulk value bag. This treat is 95% wild Alaska salmon with Glucosamine and Chondroitin. The treats are easy to cut up into litle pieces, requires no refrigeration, and are a good source for natural omega 3 and 6 fatty acids!
Available (sometimes) at Costco
Lamb and Rice Jerky by Sunshine Mills
This comes in a clear container with a red lid and is available for a low price at Costco. The jerky comes in a strip about 6 or 7 inches long, and is easy to tear into little pieces. It's not a super-high-value treat for training purposes, but it can still be used for low-difficulty-level training.
Available at Costco
Wildside Salmon Training Treats for Dogs

These are bite-sized freeze-dried bits of salmon that dogs love. These treats have a strong salmon smell so they are quite motivating for dogs.
http://www.wildsidesalmon.com/retailcatalog.html
Available at Crazy Canine (Aiea)
Real Meat Treat Jerky series (and other jerkies)

http://www.realmeatpet.com/realmeattreats.htm
Available at Crazy Canine (Aiea)
Crazy Canine Chicken Jerky
Dogs love these chicken treats. Made in Hawaii, these treats are made with 100% chicken breast meat. Sliced thin and dried for 10 hours for a delicious crunchy snack. No preservatives, salt, nor sugar, just chicken. Because the chicken is dried, I tend to use this treat during training rather than dog walks. During walks the dogs are running around and panting, so if they eat a dry treat like this, sometimes they swallow too fast and start coughing.
Available at Crazy Canine in Aiea
Pet Botanics Omega Salmon Treats
Dogs love Cardinal Laboratories’ unique 5-layer Pet Botanics Healthy Omega Treats, especially this salmon flavor. It is stinky and easy to cut into smaller pieces. They contain no wheat, soybean, glutens, grains, or artificial flavor. They offer Omega 3 and 6 fatty acids and antioxidants that make your dog’s coat shine. Ingredients include salmon sweet potato, and cod.
Available online
Stewart's Beef Liver Treats (Freeze Dried)
These freeze dried liver treats come in something resembling a plastic yogurt container. The liver has a strong smell, even if it's dried, and I have yet to meet a dog who doesn't love it. The treats come in approximately 3/4 inch pieces, but you can easily cut them up with a knife to get more mileage out of the treats.
Available at Feed Trough (Waialua), Pets R Us (Mililani) and many other pet stores
Plato Salmon Strips and Plato Thinker Sticks
Over 90% salmon, these treats are very smelly and flavorful. The strips are easy to tear into pieces, and are perfect for training and for nose work. Also sold in chicken and duck flavors.

"Enhanced" Kibble
Place the dog's food ration in a Ziploc bag. Drizzle some chicken or beef soup stock over the kibble, but not so much as to make it soupy. Shake the bag up so the soup stock gets on all the kibble, then use the kibble as training treats. You can also change the taste up by cutting up a few pieces of hot dog or meat and then microwaving it. Put those pieces into the Ziploc bag with the kibble and shake it up. Then remove the hot dog.